The invention relates generally to a method for treating fission waste and, more particularly, to a method of recovering valuable materials such as palladium, rhodium, ruthenium, and technetium from fission waste while simultaneously incorporating the remainder of the waste in a glass suitable for long-term storage.
The precious metals content of nuclear reactor waste is considerable. For example, one metric ton of spent nuclear fuel may contain about 2 Kg ruthenium, 0.5 Kg rhodium, 1.5 Kg palladium, and 0.5 Kg technetium. There is an increasing demand for these metals because of their unique properties as catalysts in various chemical processes. However, only limited quantities of these metals are available in the United States. Some, such as R. H. Moore in U.S. Pat. No. 3,848,048, have suggested recovering these metals from aqueous fission waste using chelating agents absorbed on a carbon bed.
A second problem with fission waste is the long-term safe storage of this radioactive material. Some, including Ross in U.S. Pat. Nos. 4,094,809, Schulz in 4,020,004, and Barney in 4,020,265, have suggested the incorporation of radioactive waste in glass or mineral matrix. These products are designed to be thermally stable and highly insoluble so that radioactive waste may be stored for extremely long periods of time with very little chance of adverse environmental impact. The above-referenced patents are incorporated herein by reference.
It is accordingly, an object of this invention to provide a method for recovering palladium, rhodium, ruthenium, or technetium from radioactive fission waste.
It is another object of this invention to provide a method for incorporating radioactive fission waste in a stable leach-resistant solid suitable for long-term storage.
It is an advantage of this invention that valuable metals may be recovered from radioactive fission waste at the same time the waste is being prepared for long-term storage without the addition of excess chemicals which unnecessarily add to the waste disposal problem and without resort to messy aqueous chemistry methods.
Other objects, advantages, and novel features of the invention will be apparent to those of ordinary skill in the art upon examination of the following detailed description of a preferred embodiment of the invention and the accompanying drawing.